he one difference in the syntax from the 'apply load' code block is that the name of the parameter sidelfaces has been replaced with faces. Remember the RegionO method returns a set-like region or a surface-like region depending on the parameters as explained in the 'apply load' section. In this case we apply the encastre constraint on the returned Region object. Since encastre is performed on the set of points and not just the surface, we need RegionO to return a set-like region.